(1) Field of the Invention
The present invention relates to a process and apparatus for preparing phenols from .alpha.-hydroxyalkyl-substituted aromatic compounds and/or .alpha.,.beta.-unsaturated alkyl-substituted aromatic compounds.
(2) Description of the Prior Art
It is known that when an .alpha.-hydroxyalkyl-substituted aromatic compound (often called "aromatic compound" hereinafter) and/or an .alpha.,.beta.-unsaturated alkyl-substituted aromatic compound (often called "aromatic unsaturated compound" hereinafter) is reacted with hydrogen peroxide in the presence of an acidic catalyst, a phenol is formed (see, for example, the specification of British Pat. No. 910,735). Since such aromatic alcohol or aromatic unsaturated compound is formed as a by-product when an alkyl aromatic compound is oxidized to a corresponding hydroperoxide with molecular oxygen, when a phenol is prepared by acid decomposition of the so formed hydroperoxide, the yield based on the starting alkyl aromatic compound will be increased if this by-product can be converted to the phenol. Accordingly, this process utilizing the above-mentioned reaction with hydrogen peroxide is very attractive. However, since hydrogen peroxide is a strong oxidant, the once formed phenol is reacted with this hydrogen peroxide, resulting in reduction of the yield of the phenol or degradation of the quality of the phenol due to formation of coloring impurities. Especially, when the volume of the reaction vessel is increased, it becomes difficult to advance the intended reaction at a high efficiency while controlling undesired side reactions.